Working Memory Demands Impair Skill Acquisition in Children with ADHD

This study was designed to test the hypothesis that working memory (WM) deficits in children with ADHD impair their acquisition of complex cognitive skills. Participants were 32 children with the combined subtype of ADHD, 21 with the inattentive subtype, and 48 control children without the disorder; all were between 8 and 12 years of age.

Participants completed 2 tasks that required them to learn a new arithmetic skill; each task was similar in overall difficulty but differed in the demands placed on children’s WM. The authors predicted that children with ADHD – who are known to have deficits in WM – would have more difficulty learning the task that with greater WM demands, and would be less impaired on the low WM task. In particular, they expected that children with ADHD would not learn the WM dependent skill to the degree that their performance became ‘automatic’, i.e., they would not advance to the point where they solved problems immediately and accurately but would instead need to go through a more deliberate problem solving process each time.

Overall, the performance of children with ADHD was slower and they made more errors on both tasks. However, as predicted, “…significant group differences in the pattern of skill acquisition were seen for the high but not the low WM load task.” Specifically, children with ADHD were less able to ‘automatize’ the WM dependent skill to the degree that their responses became increasingly quick and accurate (think of the difference between children who have memorized the multiplication tables to the degree that they can immediately provide the correct answers to problems rather than having to work out solutions more deliberately in their head). This was especially true for children with the inattentive subtype of ADHD.

This study is the first to demonstrate that children with ADHD are especially prone to struggle in the acquisition of cognitive skills that place high demands on WM. The authors state “…the results of the current investigation suggest that the development of automaticity for complex cognitive processes is in fact impaired in children with ADHD and that the severity of this impairment is directly dependent upon the WM load requirements of a given task.” Their findings have important implications for instructional strategies for children with ADHD, including finding ways to reduce WM load during learning. These results also highlight the potential value of training WM in children with ADHD, as this may also assist them in the acquisition of complex cognitive skills.